Evaluation of bone bruises and associated cartilage in anterior cruciate ligament-injured and -reconstructed knees using quantitative t(1ρ) magnetic resonance imaging: 1-year cohort study.

PURPOSE: To quantitate bone marrow edema-like lesions (BMELs) and the radiologic properties of cartilage in knees with acute anterior cruciate ligament (ACL) injuries using T(1ρ) magnetic resonance imaging over a 1-year period. METHODS: Nine patients with ACL injuries were studied. Magnetic resonance imaging scans were acquired within 8 weeks of the injury, after which ACL reconstruction surgery was performed. Images were then acquired 0.5, 6, and 12 months after reconstructions. The volume and signal intensity of BMELs were quantified at baseline and follow-up examinations. T(1ρ) values were quantified in cartilage overlying the BMEL (OC) and compared with surrounding cartilage at all time points. RESULTS: BMELs were most commonly found in the lateral tibia and lateral femoral condyle. Nearly 50% of BMELs resolved over a 1-year period. The T(1ρ) values of the OC in the lateral tibia, medial tibia, and medial femoral condyle were elevated compared with respective regions in surrounding cartilage at all time points; the difference was significant only in the lateral tibia (P < .05). The opposite results were found in the lateral femoral condyle. For the medial tibia and medial femoral condyle, none of the time periods was significantly different. The percent increase in T(1ρ) values of OC in the lateral tibia was significantly correlated with BMEL volume (r = 0.74, P < .05). At 1 year, the OC in the lateral tibia, medial tibia, and medial femoral condyle showed increased T(1ρ) values despite improvement of BMEL. CONCLUSIONS: In patients after ACL tear and reconstruction, (1) the cartilage overlying BMEL in the lateral tibia experiences persistent T(1ρ) signal changes immediately after acute injuries and at 1-year follow-up despite BMEL improvement, (2) the superficial layers of the overlying cartilage show greater matrix damage than the deep layers, and (3) the volume of the BMEL may predict the severity of the overlying matrix's damage in the lateral tibia. T(1ρ) is capable of quantitatively and noninvasively monitoring this damage and detecting early cartilage changes in the lateral tibia over time. LEVEL OF EVIDENCE: Level IV, therapeutic case series.

Longitudinal assessment of bone marrow edema-like lesions and cartilage degeneration in osteoarthritis using 3 T MR T1rho quantification.

OBJECTIVE: To quantitatively assess the relationship between bone marrow edema-like lesions (BMELs) and the associated cartilage in knee osteoarthritis (OA) using T(1rho) quantification at 3 T MRI. MATERIALS AND METHODS: Twenty-four patients with knee OA and 14 control subjects underwent 3 T MRI. Nineteen patients and all control subjects had 1-year follow-up studies. The volume and signal intensity difference of BMELs were calculated. Cartilage degeneration was graded using the cartilage subscore of Whole-Organ MRI Score (WORMS) analysis. Cartilage T(1rho) values were calculated in each compartment as well as in cartilage overlying BMELs (OC) and surrounding cartilage (SC). RESULTS: At baseline, 25 BMELs were found in 16 out of 24 patients. The overall T(1rho) values were significantly higher in patients with BMELs than in those without BMELs. At baseline and follow-up, both T(1rho) values and WORMS cartilage subscore grading were significantly higher in OC than SC. Cartilage T(1rho) increase from baseline to follow-up in OC was significantly higher than that in SC. An increase in T(1rho) values in OC was correlated with signal intensity of BMEL at both baseline and follow-up, but was not correlated with BMEL volume. CONCLUSIONS: The results of this study suggest a local spatial correlation between BMELs and more advanced and accelerated cartilage degeneration. MRI T(1rho) quantification in cartilage provides a sensitive tool for evaluating such correlations.

Quantitative MRI using T1ρ and T2 in human osteoarthritic cartilage specimens: correlation with biochemical measurements and histology.

PURPOSE: A direct correlation between T(1ρ), T(2) and quantified proteoglycan and collagen contents in human osteoarthritic cartilage has yet to be documented. We aimed to investigate the orientation effect on T(1ρ) and T(2) values in human osteoarthritic cartilage and to quantify the correlation between T(1ρ), T(2) vs. biochemical composition and histology in human osteoarthritic cartilage. MATERIALS AND METHODS: Thirty-three cartilage specimens were collected from patients who underwent total knee arthroplasty due to severe osteoarthritis and scanned with a 3T MR scanner for T(1ρ) and T(2) quantification. Nine specimens were scanned at three different orientations with respect to the B(0): 0°, 90° and 54.7°. Core punches were taken after MRI. Collagen and proteoglycan contents were quantified using biochemical assays. Histology sections were graded using Mankin scores. The correlation between imaging parameters, biochemical contents and histological scores were studied. RESULTS: Both mean T(1ρ) and T(2) at 54.7° were significantly higher than those measured at 90° and 0°, with T(1ρ) showing less increase compared to T(2). R(1ρ) (1/T(1ρ)) values had a significant but moderate correlation with proteoglycan contents (R=.45, P=.002), while R(2) (1/T(2)) was not correlated with proteoglycan. No significant correlation was found between relaxation times (T(1ρ) or T(2)) and collagen contents. The T(1ρ) values of specimen sections with high Mankin scores were significantly higher than those with low Mankin scores (P<.05). CONCLUSIONS: Quantitative MRI has a great potential to provide noninvasive imaging biomarkers for cartilage degeneration in osteoarthritis.

In vivo T1rho quantitative assessment of knee cartilage after anterior cruciate ligament injury using 3 Tesla magnetic resonance imaging.

OBJECTIVE: The aims of this study were to evaluate the spatial distribution of cartilage structure in controls and patients, and to quantitatively assess the cartilage overlying bone marrow edema-like lesion (BMEL) and within defined cartilage compartments in knees with anterior cruciate ligament (ACL) tears using T1rho mapping technique at 3 T magnetic resonance imaging. MATERIALS AND METHODS: The knee joints of 15 healthy controls (4 women, 11 men, mean age = 30.1 year) and 16 patients with ACL tear (5 women, 11 men, mean age = 32.5 years) who showed BMEL was studied using a 3 T GE MR scanner and a quadrature knee coil. The imaging protocol included sequences for cartilage morphology and 3D quantitative T1rho mapping. Lateral femoral condyle and medial femoral condyles compartments were partitioned into anterior and posterior nonweight-bearing (ant-nwb and postnwb) portions and weight-bearing (wb) portions in all subjects. In patients only, cartilage overlying BMEL and surrounding cartilage portions were also defined. T1rho values were quantified in cartilage overlying BMEL and surrounding compartments and in each defined compartment of the ACL-injured knees, and compared with controls. RESULTS: Significantly elevated T1rho values were found in the femoral nonweight-bearing (nwb) portions when compared with weight-bearing (wb) portions both in patients and controls. Significantly increased T1rho values were found in cartilage overlying BMEL when compared with surrounding cartilage at the lateral tibia (LT), but no difference was found in the lateral femoral condyle. CONCLUSION: T1rho mapping technique provides tools to quantitatively evaluate the cartilage matrix overlying BMEL in patients with ACL injuries. Cartilage abnormalities are already present following initial ACL injuries over the lateral tibia. Quantitative MRI can allow critical evaluation of medical and surgical treatments for ligament and degenerative conditions of the knee.

Quantitative assessment of bone marrow edema-like lesion and overlying cartilage in knees with osteoarthritis and anterior cruciate ligament tear using MR imaging and spectroscopic imaging at 3 Tesla.

PURPOSE: To quantitatively assess bone marrow edema-like lesion (BMEL) and the overlying cartilage in osteoarthritis (OA) or anterior cruciate ligament (ACL)-injured knees using magnetic resonance imaging (MRI) and spectroscopic imaging (MRSI). MATERIALS AND METHODS: Eight healthy controls and 30 patients with OA and other injuries who showed BMEL were scanned at 3.0T. A regression model was constructed to automatically calculate the volume of BMEL. Normalized T(1rho) z-scores were calculated within BMEL-overlying cartilage. Three-dimensional (3D) MRSI was acquired in the BMEL and surrounding bone marrow. RESULTS: The mean T(1rho) z-score was significantly higher in BMEL-overlying cartilage than that in surrounding cartilage in the lateral tibia of patients with ACL tears (P < 0.001). Significantly elevated water and unsaturated lipids, and decreased saturated lipids were observed in BMEL. The volume of elevated water correlated with the volume of BMEL. Water content was significantly higher within BMEL than that outside BMEL. The unsaturation index outside BMEL was significantly higher in patients with ACL tears than that in OA. CONCLUSION: 3D MRSI and T(1rho) mapping provide tools to quantitatively evaluate BMEL in OA and knee injury. This may allow us to better understand pathophysiology and evolution of injuries and degenerative conditions of the knee.